Within this 541-record scope, one assignee leads with 54 records, well ahead of the fifth-place assignee at 19. The top five assignees combined hold 30.5% of all records, and the top ten hold 40.5%, which means the rest of the field — a further 100 companies in the ranked list — splits the remaining 60% among a long tail of smaller filers. This is a concentrated-at-the-top field with plenty of room beneath it, rather than one dominated end to end by a handful of players.

Filing peaked in 2018 at 36 records and had fallen to 18 by the 2022 midpoint, roughly half the peak, with no later rebound visible in the data through the most recent complete years. Every leading assignee tracked for recent-year momentum shows zero filings in the latest year, reinforcing the slowdown. Publication lag of roughly 18 months means the final year or two of any trend chart understates true activity, but that lag alone does not account for a multi-year decline that started years before the data cut-off.

US10442712B2, assigned to Nanjing University and granted in 2019, covers an MBR architecture built around integrated fouling control — combining a reactor wall, membrane element, collecting pipes, vacuum table, suction pump, cleaning unit, air compressor and aeration components into one system designed to avoid chemical cleaning agents. It is a useful reference point for anyone drafting a fouling-control claim, since it defines a specific hardware combination rather than a broad method, meaning filings built around different hardware integration or alternative fouling-mitigation mechanisms have room to avoid direct overlap. Any new filing in this space should still be checked against it and the other highly-cited records in this scope during drafting.

C02F (water and wastewater treatment) appears on 97.6% of the 541 records in this scope, which is expected given the search terms, and B01D (separation processes including filtration) appears on 40.5%, marking it as the strongest secondary claim area. Everything else — C12M bioreactor apparatus, B01F mixing, C01B inorganic compounds, C12P fermentation, B01J catalysis and G01N analysis — sits at or under 5.5% of records each. A thorough clearance search needs to cover both C02F and B01D at minimum, with the smaller classes worth checking depending on the specific claim being drafted.

The IPC subclasses sitting under 6% of the 541 records — C12M (bioreactor apparatus), B01F (mixing/aeration hardware), C12P (fermentation-based pre-treatment), B01J (catalytic surfaces) and G01N (analytical/sensing methods) — are comparatively thin relative to the near-universal C02F and the dense B01D. That does not guarantee an easy grant, since high filing density elsewhere means the core problem space is well mapped, but it does mean fewer prior filings to design around in those specific branches. A claim drafted around real-time fouling sensing or catalytic anti-fouling surfaces, for instance, has more open ground than one drafted around basic membrane separation hardware.